Impact of Endocrine Aging on Brain and Immune Responses

本申请的目的是确定生殖老化和雌激素替代改变炎症反应和神经元环境的机制。在一系列的研究中，我们已经确定，雌激素替代年轻的成年动物增加前脑的营养支持和减轻神经损伤后的炎症。然而，雌激素替代生殖衰老，这是生理上类似于绝经，未能增加营养因子和矛盾，增加炎症介质后神经损伤。总的来说，这些数据表明，雌激素替代的时机与生殖衰老的关系可能决定是否 雌激素具有良性或有害的结果。我们的中心假设是，与年龄相关的内源性激素下降触发了特定免疫细胞中雌激素受体系统的代偿性变化，从而增加了中枢和外周炎症反应。该假设将在三个特定目标中进行检验，使用跨越生殖谱的动物和人体组织模型，即正常循环（绝经前）。周期不规则（围绝经期）和生殖衰老（绝经后）。具体目标1。我们将检验这样的假设，即与正常循环或不规则循环的动物相比，血脑屏障的容许变化将在生殖衰老动物中引起更快速和更强烈的神经炎症。动物将全身注射细菌病原体 将在外周器官和脑中测量脂多糖（LPS）和炎性介质。此外，我们将检查血脑屏障的内皮细胞，以了解该屏障中与生殖年龄相关的变化。具体目标2。我们将确定外周血单核细胞（PBMC）的炎症反应是否受到临床相关变量的影响，即激素给药途径（口服与透皮）和饮食（常规与高胆固醇）。将在大鼠和人血液样本中测量来自离体LPS激发试验的反应商，以确定显著的生活方式变量是否会增加与生殖衰老相关的风险。最后在 具体目标3我们将测试的假设，雌激素受体系统的补偿性改变，导致卵巢功能下降，是一个主要的机制，雌激素的有害影响，在生殖衰老。雌激素受体（ER）-α的模式和水平的变化将通过免疫组织化学和蛋白质印迹法进行评估，而功能变化将使用信号阵列进行评估。将研究来自每个生殖阶段的人和啮齿动物PBMC和啮齿动物脑内皮细胞。总的来说，这些研究将检验这样一个假设，即为了使雌激素替代有益，治疗必须在卵巢功能下降的代偿反应之前开始。

The goal of this application is to determine the mechanisms by which reproductive aging and estrogen replacement alter the inflammatory response and consequently the neuronal environment. In a series of studies, we have established that estrogen replacement to young adult animals increases trophic support in the forebrain and attenuates inflammation following neural injury. However estrogen replacement at reproductive senescence, which is physiologically akin to menopause, fails to increase trophic factors and paradoxically, increases inflammatory mediators following neural injury. Collectively these data suggest that the timing of estrogen replacement in relation to reproductive aging may critically determine whether estrogen has a benign or deleterious outcome. Our central hypothesis is that the age-related decline in endogenous hormones triggers compensatory changes in estrogen receptor systems in specific immune cells, thus increasing the central and peripheral inflammatory response. This hypothesis will be tested in three Specific Aims, using animal and human tissue models that span the reproductive spectrum, namely, normally cycling (pre-menopause). irregularly cycling (perimenopause) and reproductive senescent (postmenopause). In Specific Aim 1. we will test the hypothesis that permissive changes in the blood brain barrier will cause a more rapid and robust neural inflammation in reproductive senescent animals as compared to normally cycling or irregularly cycling animals. Animals will be injected systemically with the bacterial pathogen lipopolysaccharide (LPS) and inflammatory mediators will be measured in peripheral organs and the brain. Additionally, we will examine endothelial cells of the blood-brain barrier for reproductive age-related changes in this barrier. In Specific Aim 2. we will determine if the inflammatory response of peripheral blood mononuclear cells (PBMC) is affected by clinically-relevant variables namely, the route of hormone administration (oral versus transdermal) and diet (regular versus high cholesterol). The Response Quotient, derived from an ex vivo LPS challenge assay, will be measured in rat and human blood samples to determine if salient lifestyle variables increase the risks associated with reproductive aging. Finally, in Specific Aim 3 we will test the hypothesis that compensatory alterations of the estrogen receptor system, resulting from ovarian decline, is a principal mechanism underlying estrogen's deleterious effects in reproductive senescence. Changes in the pattern and levels of estrogen receptor (ER)-alpha will be evaluated by immunohistochemistry and Western blots, while functional changes will be evaluated using signaling arrays. Human and rodent PBMC's and rodent cerebral endothelial cells from each reproductive stage will be studied. Collectively, these studies will test the hypothesis that in order for estrogen replacement to be beneficial, therapy must be initiated before compensatory responses to ovarian decline.